Tool

1. Tool ( 1 ), in particular an impact wrench,

with a pulse unit ( 6 ) having a hydraulic impact mechanism ( 7 ) and a drive unit ( 24 ),

wherein a working volume ( 5 ) within the hydraulic impact mechanism ( 7 ) can be connected to an additional volume ( 4 ) formed outside of the hydraulic impact mechanism,

wherein the additional volume ( 4 ) has setting means ( 2 ) comprising a manually adjustable piston ( 2 ) that limits one end of the additional volume ( 4 )

characterised in that,

at least the additional volume ( 4 ) can be varied independently of a pressure of a working fluid.

2. Tool ( 1 ) according to claim 1 , characterised in that the hydraulic impact mechanism ( 7 ) is arranged between the drive unit ( 24 ) and a tool holder ( 25 ).

3. Tool ( 1 ) according to claim 1 , characterised in that the additional volume ( 4 ) can be enlarged and reduced by the setting means ( 2 ).

4. Tool ( 1 ) according to claim 1 , characterised in that the piston ( 2 ) can be set via an external and/or internal thread relative to the hydraulic cylinder ( 11 ).

5. Tool ( 1 ) according to claim 4 , characterised in that the hydraulic cylinder ( 11 ) has at least four fixable rotary positions ( 16 ) which are arranged offset, in particular by 90°.

6. Tool ( 1 ) according to claim 4 , characterised in that the piston ( 2 ) has an internal thread, which can be screwed onto an external thread of the hydraulic cylinder ( 11 ).

7. Tool ( 1 ) according to claim 1 , characterised in that the additional volume ( 4 ) is arranged between the hydraulic cylinder ( 11 ) and the piston ( 2 ).

8. Tool ( 1 ) according to claim 7 , characterised in that the piston ( 2 ) has an outer limb profile which forms a chamber ( 3 ) and ( 4 ) with the hydraulic cylinder ( 11 ) for reserve oil and compensating oil.

9. Tool ( 1 ) according to claim 1 , characterised in that the piston ( 2 ) is manufactured from a resilient, stiff and low-mass material, in particular hard anodised aluminium.

10. Tool ( 1 ) according to claim 1 , characterised in that the piston ( 2 ) is sealed relative to the hydraulic cylinder ( 11 ) with O-ring seals ( 13 , 14 ).

11. Tool ( 1 ) according to claim 1 , characterised in that the piston ( 2 ) can be fixed in at least one rotary position ( 16 ).

12. Tool ( 1 ) according to claim 11 , characterised in that the piston ( 2 ) is fixed in at least one rotary position ( 16 ) relative to the hydraulic cylinder ( 11 ).

13. Tool ( 1 ) according to claim 12 , characterised in that the piston ( 2 ) is fixed in at least one rotary position ( 16 ) relative to the hydraulic cylinder ( 11 ) by means of a locking element ( 15 ).

14. Tool ( 1 ) according to claim 13 , characterised in that the locking element ( 15 ) is a pin, sleeve or threaded stud.

15. Tool ( 1 ) according to claim 13 , characterised in that the piston ( 2 ) has at least one receptacle opening or groove for the locking element ( 15 ).

16. Tool ( 1 ) according to claim 13 , characterised in that the piston ( 2 ) can be fixed relative to the hydraulic cylinder ( 11 ) with the locking element ( 15 ) after setting the pulse rate.

17. Tool ( 1 ) according to claim 1 , characterised in that the piston ( 2 ) can be rotated with an auxiliary tool to change the volume.

18. Tool ( 1 ) according to claim 1 , characterised in that the piston ( 2 ) has an essentially L-shaped profile.

19. Tool ( 1 ) according to claim 1 , characterised in that the piston ( 2 ) has two cylindrical internal diameters of different size.

20. Tool ( 1 ) according to claim 19 , characterised in that at least one of the internal diameters of the piston ( 2 ) has a groove for an O-ring seal ( 13 , 14 ).

21. Tool ( 1 ) according to claim 19 , characterised in that at least one of the internal diameters of the piston ( 2 ) has a mounting surface for an O-ring seal ( 13 , 14 ).

22. Tool ( 1 ) according to claim 1 , characterised in that the reserve oil, the oil compensating volume and the increase in pulse frequency can be set simultaneously with the piston ( 2 ).